The present invention relates to finned tube heat exchangers and particularly relates to air cooled heat exchangers having increased heat transfer coefficients achieved by increasing the finned surface area.
Heat exchangers having finned tubes providing heat exchange between a hot flowing fluid within the tubes and cooling air flowing about the tubes and the fins are well known. Such heat exchangers are typically manufactured by grooving the external wall of the tube and applying fin material pressed on-edge into the groove. The tube may be spirally grooved or provided with plural annular grooves for receiving the fin or fins. Alternatively, steel tubes are often coated with an aluminum jacket which is shrink fit onto the tube. Fins are extruded from the aluminum material, i.e., the aluminum material is deformed to form the fins.
It is desirable in many instances to enhance the heat transfer, i.e., increase the heat transfer coefficient, in these types of heat exchangers. However, methods to effect increased heat transfer rate or heat transfer coefficient in many products have the undesirable effect of incurring a large pressure drop penalty. Thus, airflows about the tube and fins, particularly fins having surface irregularities, pay a high cost in pressure drop to increase the heat transfer rate. Accordingly, it is desirable to provide a finned heat exchanger having enhanced thermal effectiveness with little or no added pressure loss in the fin tube bundle.